Method for operating a cabin air filter system for a vehicle, computer program, electronic control unit, cabin air filter system, and vehicle
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-02-08
- Publication Date
- 2026-03-10
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a method of operating a cabin air filter system for a vehicle, the cabin air filter system comprising an air filter device for filtering an air flow entering a passenger compartment, the air flow being made up of fresh air from outside the passenger compartment and recirculated air from inside the passenger compartment, the magnitude of the air flow passing through the air filter device being adjustable, and the ratio of fresh air to recirculated air in the air flow passing through the air filter device being adjustable. [Background technology]
[0002] Such a cabin air filter system is known from WO 2018 / 224299. The system according to WO 2018 / 224299 comprises three filter elements, some of which can be selectively bypassed. Furthermore, the ratio of fresh air to recirculated air is adjustable.
[0003] Typically, existing strategies used to control HVAC systems (heating, ventilation, and air conditioning) are to calculate the blower speed and air recirculation ratio for thermal and acoustic comfort and humidity control. Air quality may also be addressed by closing flaps in 100% reuse / recirculation mode. Furthermore, it is known that air conditioning increases the energy consumption of a vehicle.
[0004] For example, after a cold start, it is important to prioritize humidity management to prevent fogging and even achieve windshield defrosting. Fogging or frost on the windshield reduces the driver's visibility and affects driving safety. In low temperature situations, 100% cold air from the outside (the colder the air, the less humid it is) or air conditioning upstream of the heater can be used to dry the air. In high temperature situations, air conditioning can be used only in 100% reuse mode to dry the air and at the same time reduce the temperature. Such strategies are only used for a few minutes after cold start, which is usually combined with maximum airflow and generates high noise levels. As these effects are related to safety, high noise emissions are usually tolerated. During range, the airflow is usually limited to about 50% of the maximum airflow due to acoustic constraints.
[0005] US 2012 / 0009859 A1 discloses a system and method for selecting air inlet between 100% fresh air mode and 100% recirculated air mode to achieve optimal heating / cooling performance, fuel economy, and / or high voltage (HV) battery power consumption. The system and method includes a partial recirculation control strategy that incrementally moves the air inlet door to a desired position, taking into account the heating / cooling load and the probability of fogging in the vehicle cabin. When the heating / cooling load increases, the air inlet door moves to 100% recirculation mode. When the probability of fogging increases, the air inlet door moves to 100% fresh air mode. By selectively choosing a position between 100% recirculation and 100% fresh air, fuel economy and HV battery power consumption are optimized without compromising passenger comfort or fogging the vehicle interior glass.
[0006] US 2004 / 0065204 describes an air quality monitor for an enclosed cab of an agricultural tractor used to tow or carry a spraying implement for treating crops with substances that may be toxic or harmful to humans. A signal from a pollutant sensor is sent to a control device, which compares the sensed air pollution in the cab over time with values from a performance map representing the expected performance of the cab's air circulation system under normal conditions. If the sensed pollution level is higher than the performance map value, a fault warning is issued to the driver. The blower of the air circulation system can increase its speed to pressurize the cab, preventing the ingress of polluted air through small openings such as the cab seal. The air filters used are coded and recognized by the control device. The control device records the time of use of the filter and issues a warning to the driver when the time of use exceeds a time value stored in association with a particular filter.
[0007] An object of the present invention is to meet the air quality requirements within the vehicle cabin with minimal energy consumption.
[0008] This is achieved by a method for operating a cabin air filter system of a vehicle according to claim 1, a computer program for controlling a cabin air filter system of a vehicle according to claim 22, an electronic control unit for a cabin air filter system of a vehicle according to claim 24, a cabin air filter system according to claim 26 and a vehicle according to claim 27. Advantageous embodiments are set out in the dependent claims and in the description. Summary of the Invention
[0009] According to the present invention there is provided a method of operating a cabin air filtration system in a vehicle, for example the vehicle being a car, van or bus.
[0010] The cabin air filter system includes an air filter device that filters the airflow entering the vehicle cabin. The airflow passing through the air filter device is composed of fresh air from outside the vehicle cabin and recirculated air from inside the vehicle cabin. In other words, the fresh air from outside the vehicle cabin and the recirculated air from inside the vehicle cabin are filtered by the air filter device and blown out (returned) into the vehicle cabin. The air filter device includes at least one air filter element.
[0011] The magnitude of the air flow through the air filter device can be adjusted. For this purpose, a blower device can be employed. The magnitude of the air flow refers to the amount of fresh and recirculated air filtered by the air filter device and can be measured as volume or mass per time.
[0012] The ratio of fresh air to recirculated air in the airflow through the air filter device is adjustable. As mentioned above, the airflow through the air filter device is composed of fresh air and recirculated air. The ratio of these two components can be adjusted to only fresh air, only recirculated air, or any ratio in between. Adjustment of the recirculation ratio of fresh air to recirculated air can be made continuously. For this purpose, a flow ratio adjustment device can be employed.
[0013] The total inflow of air from the outside can enter the vehicle cabin as a filtered inflow through the air filter device and an unfiltered inflow bypassing the air filter device. The filtered inflow is fresh air that passes through the air filter device and is filtered there. The unfiltered inflow enters the vehicle cabin without passing through the air filter device. The unfiltered inflow can enter the vehicle cabin through seals of openings (such as doors and windows), wires, hoses, etc., especially at the front of the vehicle. Since the unfiltered inflow does not pass through the air filter device, it carries pollutants (particles of various sizes, harmful gases, odors, etc.) into the vehicle cabin.
[0014] In step A) of the method, At least one characteristic of the air filter device, the characteristic including information regarding the overall filtering efficiency of the total inflow of air from the outside into the vehicle compartment; a magnitude of airflow through the air filter device; and Vehicle speed and System information relating to the proportion of fresh air versus recirculated air is provided.
[0015] The overall filtering efficiency depends on the magnitude of the air flow through the air filter device, the vehicle speed, and the ratio of fresh air to recirculated air. The relationship between these values is included in the system information. The magnitude of the unfiltered inflow depends in particular on the vehicle speed and the magnitude of the air flow through the air filter device. The magnitude of the unfiltered inflow, which depends on these values, can be included explicitly or, preferably, implicitly in the system information. The overall filtering efficiency can also be called the "overall apparent effective cabin filtering efficiency".
[0016] The system information may be obtained from experiments and / or simulations. The system information may be provided per pollutant, i.e. for different pollutants, the respective relationships of the aforementioned values may be included in the system information. The system information describes inter alia the functional interdependencies of the associated cabin air filtration system.
[0017] The overall filtration efficiency is not the pure physical separation efficiency exhibited by the filter device with respect to the filtered inflow, but rather the resulting filtration efficiency that takes into account both the actual filtered volumetric flow (filtered inflow) and the estimated impact of the unfiltered volumetric flow (unfiltered inflow) that adversely affects the "resulting", "substantial" or "effective" filtration efficiency that can actually be achieved. In particular, the overall filtration efficiency includes at least a dependence on the vehicle speed, the recirculation ratio, and the magnitude of the air flow through the air filter device.
[0018] In step B) of the method, a required vehicle filtration efficiency is provided. In particular, the required vehicle filtration efficiency specifies how much of the contaminant content in the fresh air needs to be removed from the total inflow in order to achieve a given air quality in the vehicle cabin. This required vehicle filtration efficiency is based on the air quality outside the vehicle and the required air quality in the vehicle cabin. The required vehicle filtration efficiency can also be called the "overall apparent target interior filtration efficiency". The required filtration efficiency can be provided (directly or indirectly) by a user of the vehicle or by an electronic control unit of the cabin air filter system.
[0019] In step C), a recirculation ratio of fresh air and recirculated air is determined from the system information for the current vehicle speed and the current magnitude of the air flow through the air filter device such that the overall filtration efficiency corresponds to the required vehicle filtration efficiency provided in step B). The cabin air filter system can be operated with this recirculation ratio. By evaluating the system information, it is necessary to use as much recirculated air or fresh air as necessary to obtain the desired air quality in the vehicle cabin. In particular, by using as much recirculated air as possible, the required air quality in the vehicle cabin can be maintained while minimizing energy consumption for cooling or heating.
[0020] In particular, the method according to the invention ensures that the overall filtration efficiency is always high and at least equal to or as close as possible to the required vehicle filtration efficiency. If the primary objective is to protect filter life (e.g., of a HEPA filter element in a filter system), then the overall filtration efficiency should not be higher than the required filtration efficiency. With closed-loop control of the target efficiency, it is possible to achieve air quality goals while aiming to extend filter life. If reaching the highest or best air quality is the main objective, the overall filtration efficiency should be higher than or at least equal to the required filtration efficiency, which generally corresponds to the case of open loop operation. Under certain circumstances (e.g. open windows, poor door seals, etc.) the efficiency target may not be achievable, however the overall filtration efficiency will be as close as possible to the required filtration efficiency.
[0021] The system information may include a multi-dimensional data array with the ratio of fresh air to recirculated air as an output value. Other parameters of the data array (e.g. overall filtration efficiency, magnitude of airflow through the air filter device, vehicle speed) are used as input parameters, i.e. the data array is evaluated with respect to the current values of these parameters. In this way the system information can be easily established and evaluated. Typically the data array is stored in the electronic control unit of the cabin air filter system. The data array may be represented in the form of a map or a characteristic diagram.
[0022] As used herein, associated data may refer to data that is functionally related. For example, at least one characteristic of an air filter device (e.g., a data point of overall filtration efficiency) may be correlated with a particular airflow magnitude, vehicle speed, and ratio of fresh air to recirculated air. Such multiple data points may be associated, for example, in a database, a matrix, a multi-dimensional array, a map, a graph, or a combination thereof.
[0023] According to various embodiments, an interpolation method can be used to determine the recirculation ratio of fresh air to recirculated air, allowing efficient and accurate evaluation of system information when input values (e.g., vehicle speed, airflow magnitude, recirculation ratio) deviate from the values for which the data array was created.
[0024] In an advantageous variant of the method, at predefined time intervals, a recirculation ratio of fresh air to recirculated air is determined and the flow ratio is adjusted to said ratio, so that the operation of the cabin air filter system is always kept close to optimal. The time interval is selected such that the relevant input parameters do not generally change too much between two successive evaluations. For example, the time interval may be greater than or equal to 0.5 seconds and / or less than or equal to 10 seconds. In particular, the time interval is 1 second.
[0025] According to various embodiments, system information is provided for different pollutants, in particular for particles of different size ranges, allowing a more accurate determination of the recirculation ratio, in particular the recirculation ratio can be determined for different pollutants (e.g. PM1, PM2.5, PM10, PM0.1 or UFP) such that a required filtration efficiency is achieved.
[0026] According to various embodiments, the system information is updated when a new air filter element is installed in the air filter device. This ensures that the system information is up to date, for example, when a better or less expensive filter element is installed. The new system information may be provided together with the new air filter element. The updated information may be included in an RFID chip, an NFC chip, or a bar code of the new air filter element. The new air filter element may provide information, such as a download link, accessible to the control unit of the cabin air filter system, on how and / or where to obtain the updated system information. The control unit of the cabin air filter system may read the information provided together with the new filter element, for example, with an RFID reader in the housing of the filter element. An NFC reader may be installed on the outside of the housing of the filter element. The bar code may be read by a bar code reader attached to a diagnostic tool connected to the on-board diagnostic port of the vehicle. In a variant, the updated system information is provided by a mechanic at the time of installation of the new filter element, via the on-board diagnostic port or via the mobile communication system of the vehicle.
[0027] The system information may take into account aging of the vehicle and / or aging of the air filter element of the air filter device. Aging may result in increased leakage from the outside that bypasses the air filter device and / or a decrease in the filtering efficiency of the air filter device. By identifying such effects in advance and reflecting them in the system information, an optimal operating condition of the cabin air filter system can be ensured even after degradation of the vehicle and / or the air filter device.
[0028] According to various embodiments, the required filtration efficiency is provided as a function of the geographic location of the vehicle, taking into account differences in air pollution in different locations, e.g., urban areas, mountain roads, etc. Generally, areas with good air quality require a lower filtration efficiency for the vehicle to ensure adequate air quality inside the vehicle cabin.
[0029] In a preferred variant of the method, the required filtering efficiency is provided as a function of environmental pollution measurements, which allows a particularly accurate operation of the cabin air filter system. Environmental pollution information can be obtained from official measuring services and / or from an external air quality sensor of the cabin air filter system.
[0030] According to various embodiments, the required filtration efficiency is determined to meet different predefined limit values for different pollutants, in particular for particles of different size ranges (e.g. PM1, PM2.5, PM10, PM0.1, or UFP). The predefined limit values can specify the amount of the respective pollutant in the air in the vehicle cabin. This ensures that there is no excess of the pollutant in the vehicle cabin.
[0031] The required filtering efficiency may be provided depending on the settings of an electronic control unit of the cabin air filter system, in particular the settings of the electronic control unit being adjustable by a user and / or by automatic control, taking into account the respective needs.
[0032] In an advantageous variant of the method, in step C), the vehicle occupants are taken into account in order to determine the recirculation ratio between fresh and recirculated air. The more occupants, the higher the humidity and the higher the CO2 emissions. The maximum recirculation ratio may therefore be limited in order to ensure sufficient oxygen. Similarly, a limit may be set on the recirculation ratio in order to ensure that the air in the passenger compartment is sufficiently dry, depending on the outside temperature and humidity.
[0033] According to various embodiments, in step C) energy management information of the vehicle is taken into account to determine the recirculation ratio of fresh air and recirculated air. In particular, if the vehicle is a (hybrid) electric vehicle, the energy management information may include the charge level of the vehicle's traction battery. In this variant, if the energy level is low, a lower air quality is allowed in order to increase the remaining driving range.
[0034] The operation of the cabin air filter system at the recirculation ratio according to step C) may be interrupted by periods of operation of the cabin air filter system at the air recirculation ratio given to higher priority strategies, in particular demisting, defrosting, speed ventilation, or energy saving. This may disable the above-mentioned method of balancing air quality and energy consumption under certain circumstances. For example, demisting and defrosting are important for safety, so air quality and energy consumption should not compromise these functions. Similarly, speed ventilation (e.g., after the vehicle is parked in the sun) is crucial to keep comfort and driver attention high. Therefore, these tasks may be prioritized over air quality and energy saving. On the other hand, energy consumption may be given top priority if the vehicle is likely to not reach the target destination.
[0035] The air filter device may comprise a basic filter element for filtering fresh air and / or recirculated air, and a HEPA filter element and / or an ambient air filter element for filtering the fresh air. In other words, the basic filter element filters both the fresh air and the recirculated air. The HEPA filter element and / or the ambient air filter element filters only the fresh air. It is usually sufficient to filter the recirculated air with the basic filter element, since the recirculated air is already filtered when it enters the passenger compartment as fresh air. This reduces the pressure loss for blowing the recirculated air through the air filter device. Thus, energy consumption can be reduced. Filtering the fresh air with an additional HEPA filter element and / or ambient air filter element allows optimal cabin air quality to be obtained.
[0036] According to various embodiments, the ambient air filter element is disposed upstream of the HEPA filter element, so that the ambient air filter element can protect the HEPA filter element from larger particles, which contributes to extending the life of the HEPA filter element.
[0037] Furthermore, the basic filter element and / or the ambient air filter element may comprise at least one adsorbent, in particular activated carbon, which allows for the removal of harmful gases and odors from the filtered air, activated carbon being particularly efficient in this respect.
[0038] The cabin air filter system may include an interior air quality sensor and / or an exterior air quality sensor. The interior air quality sensor allows the required vehicle filtration efficiency to be provided in a specific and accurate manner. Furthermore, the interior air quality sensor can be used to provide a closed-loop control of the air quality in the cabin. This allows the air quality specifications, such as the pollutant-specific limit values, to be met accurately. The exterior air quality sensor allows the amount of pollutants entering the cabin to be accurately predicted as filtered inflow and unfiltered inflow. Thus, the required recirculation ratio can be provided accurately to keep the amount of pollutants entering the cabin from outside at an acceptable level.
[0039] According to various embodiments, in the method, the fresh air flow through the air filter device passes through or bypasses (i) the HEPA filter element and / or (ii) the ambient air filter element depending on the measurements of the cabin air quality sensor and / or the exterior air quality sensor and / or the estimated air quality outside and / or inside the cabin. If the cabin air quality is measured or estimated, the fresh air flow may be filtered by the basic filter element only if the cabin air quality meets a predefined criterion. If the cabin air quality is measured or estimated, depending on the established exterior air quality, it may be determined whether the fresh air needs to be filtered by the HEPA filter element and / or the ambient air filter element, or whether one or both of them can be bypassed to extend their life. The estimated exterior air quality may be obtained from an environmental information system (especially cloud-based).
[0040] According to various embodiments, the required vehicle filtration efficiency is provided as a function of measurements of the cabin air quality sensor and / or the exterior air quality sensor and / or estimates of the air quality outside and / or inside the cabin. This allows the required vehicle filtration efficiency to be provided in a specific and accurate manner. Furthermore, the measured or estimated air quality inside the cabin can be used for closed-loop control of the air quality inside the cabin. This allows air quality specifications, such as pollutant-specific regulatory limits, to be met accurately. The measured or estimated air quality outside the cabin allows for an accurate prediction of the amount of pollutants that will enter the cabin as filtered or unfiltered inflow. Thus, the required recirculation ratio can be provided accurately to keep the amount of pollutants entering the cabin from outside at an acceptable level.
[0041] In the method, the air quality index or the remaining life of the air filter element may be notified, in particular based on the measurements of the cabin air quality sensor. The remaining life can be provided as a time span and / or as a message that the air filter element needs to be replaced. Timely replacement of the air filter elements (in particular basic, HEPA and / or ambient air air filter elements) ensures proper functioning of the cabin air filter system and prevents the system information from deviating too much from the characteristics of the installed (outdated) filter element. The air quality index is usually calculated using a formula that combines the amounts of different pollutants, for example the number of PM1, PM2.5, PM10, NO2, O3, fine particles and ultrafine particles. The air quality index is based, for example, on the US-EPA 2016 standard. Informing the vehicle user of the air quality can increase the quality awareness of the vehicle.
[0042] According to various embodiments, at least one characteristic of the air filter device is: Efficiency curves of filter media in air filter devices; The type of filter material, the pressure loss of the air filter device as a function of the magnitude of the air flow through the air filter device; and / or It further includes information regarding the dust capacity of the air filter device.
[0043] Efficiency curves may be given for each pollutant, in particular for different size ranges of particles and / or different concentrations of harmful gases. If the air filter device comprises several air filter elements, an efficiency curve may be given for the filter medium of each air filter element. The type of filter medium may specify whether the air filter medium contains sorbents such as nanofibers and / or activated carbon, and may also specify the HEPA class of the filter medium. The pressure loss may be given depending on the (expected) dust load of the filter medium. This additional information can be used to provide a particularly accurate estimate of the required vehicle cabin filtration efficiency.
[0044] The present invention further relates to a computer program for controlling a cabin air filter system of a vehicle, the cabin air filter system comprising an air filter device for filtering an air flow entering the passenger compartment, the air flow being composed of fresh air from outside the passenger compartment and recirculated air from inside the passenger compartment, the magnitude of the air flow passing through the air filter device being adjustable, the ratio of fresh air to recirculated air in the air flow passing through the air filter device being adjustable, and the total inflow of air from outside being able to enter the passenger compartment as a filtered inflow through the air filter device and an unfiltered inflow bypassing the air filter device. The computer program is configured to cause an electronic control unit of the cabin air filter system on which the computer program is executed to: At least one characteristic of the air filter device, the characteristic including information regarding the overall filtering efficiency of the total inflow of air from the outside into the vehicle compartment; a magnitude of airflow through the air filter device; and Vehicle speed and The method includes instructions for determining, from system information relating the recirculation ratio of fresh air to recirculated air, a recirculation ratio of fresh air to recirculated air such that, for a current vehicle speed and a current airflow magnitude, the overall filtration efficiency corresponds to a required vehicle filtration efficiency, and the air filter system may operate at this ratio.
[0045] In other words, the computer program comprises commands for carrying out the above-mentioned step C) according to the invention. This computer program facilitates the execution of the method according to the invention. The computer program can be executed on an electronic control unit according to the invention as described below. In particular, the electronic control unit is part of a cabin air filter system according to the invention as described further below.
[0046] The system information may be implemented in a computer program or may be retrieved from a database, for the latter the computer program may contain commands causing the electronic control unit to access an external database, for example via a mobile communication system.
[0047] The computer program may be stored in an internal memory of the electronic control unit. Alternatively, the computer program may be stored in a computer readable storage medium. The invention also relates to a computer readable storage medium having a computer program stored thereon.
[0048] According to various embodiments, the computer program further comprises instructions for causing the electronic control unit, on which the computer program is executed, to determine the required filtration efficiency. In other words, the computer program comprises commands for carrying out the above-mentioned step B) according to the invention, which further facilitates the execution of the method according to the invention.
[0049] The present invention further relates to an electronic control unit for a cabin air filter system of a vehicle, the cabin air filter system comprising an air filter device for filtering an air flow entering the passenger compartment, the air flow being composed of fresh air from outside the passenger compartment and recirculated air from inside the passenger compartment, the magnitude of the air flow passing through the air filter device being adjustable, the ratio of fresh air to recirculated air in the air flow passing through the air filter device being adjustable, and the total inflow of air from outside being able to enter the passenger compartment as a filtered inflow through the air filter device and an unfiltered inflow bypassing the air filter device. At least one characteristic of the air filter device, the characteristic including information regarding the overall filtering efficiency of the total inflow of air from the outside into the vehicle compartment; a magnitude of airflow through the air filter device; and Vehicle speed and From the system information relating the recirculation ratio of fresh air to recirculated air, the air filter system is configured to determine a recirculation ratio of fresh air to recirculated air such that the overall filtration efficiency corresponds to a required filtration efficiency for a current vehicle speed and a current air flow magnitude, and the air filter system can operate at this ratio.
[0050] In other words, the electronic control unit is configured to execute step C) of the above-mentioned method according to the invention. The control unit allows for convenient and efficient execution of the method according to the invention. The system information may be stored in the electronic control unit or may be retrieved from a remote database. For the latter, the electronic control unit may be configured to access an external database, for example via a mobile communication system.
[0051] According to various embodiments, the electronic control unit is further configured to determine the required filtration efficiency, in other words, to execute step B) of the above-mentioned method according to the invention, which further facilitates the execution of the method according to the invention.
[0052] The present invention also provides a cabin air filter system, comprising: an air filter device for filtering an air flow that flows into a vehicle cabin and is made up of fresh air from outside the vehicle cabin and recirculated air from inside the vehicle cabin; a blower for adjusting the magnitude of airflow through the air filter device; a flow ratio adjusting device for adjusting the ratio of fresh air to recirculated air in the airflow through the air filter device; The present invention also relates to a cabin air filter system comprising an electronic control unit as described above.
[0053] The cabin air filter can be used to carry out the method according to the invention.The cabin air filter system makes it possible to supply high quality air to the passenger compartment of a vehicle equipped with the cabin air filter system in an energy efficient manner.
[0054] Other advantages and features of the invention will be understood from the following description of the embodiments of the invention, with reference to the drawings showing important details, and from the claims. The individual features as mentioned above or below may be implemented separately or in any useful combination in the variants of the invention. [Brief description of the drawings]
[0055] [Figure 1] FIG. 1 is a schematic diagram illustrating a vehicle having a cabin air filtration system with a basic filter element, a HEPA filter element, and an ambient air filter element, where filtered inflow from the outside is directed through all three filter elements and recirculated air from inside the vehicle cabin is directed only through the basic filter element, and where the recirculation ratio of fresh air to recirculated air is adjusted in accordance with the present invention. [Diagram 2] From FIG. 1 is a schematic diagram of a vehicle in which fresh air passes through an ambient air filter element and a basic filter element, bypassing the HEPA filter element. [Diagram 3] 2 is a schematic diagram of a flow chart of a method of operating a cabin air filtration system in accordance with the present invention; [Figure 4] FIG. 1 is a schematic diagram of the overall filtration efficiency of the total inflow of fresh air from outside, partially passing through and partially bypassing the cabin air filter system, for PM10 size particles at a given vehicle speed. [Diagram 5] This is a schematic diagram of measurements of PM0.1 particles at the same vehicle speed as in Figure 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0056] 1 shows a vehicle 10. The vehicle includes a cabin air filtration system 12. The interior of the vehicle 10 defines a passenger compartment 14. Passengers 16, 18 are seated in the passenger compartment 14.
[0057] The cabin air filtration system 12 includes an air filtration apparatus 20. A total inflow 22 of fresh air from an outside environment 24 enters the vehicle interior as a filtered inflow 26 that passes through the air filtration apparatus 20 and an unfiltered inflow 28 that bypasses the air filtration apparatus 20.
[0058] Air from within the passenger compartment 14 is recirculated through the air filter arrangement 20 in a recirculated air flow 30. A flow ratio adjustment device 32 is provided for adjusting the ratio of the recirculated air flow 30 to the filtered inflow 26. The flow ratio adjustment device 32 is shown here diagrammatically with two movable flaps 34, 36.
[0059] The filtered inflow 26 and the recirculated air flow 30 together constitute a filtered air flow 38 passing through the air filter apparatus 20. A blower 40 is provided to regulate the magnitude of the air flow 38 passing through the air filter apparatus 20. The magnitude may be given, for example, as a volume or mass of air per time. The magnitude of the air flow 38 may be measured by a flow meter (not shown).
[0060] Alternatively, the magnitude of the airflow may be estimated. To this end, the voltage and current applied to the blower 40 may be measured. Additionally, the temperature of the air in the external environment 24 may be measured. The density of the external air may be measured or calculated from the temperature. Similarly, the temperature and density of the air within the passenger compartment 14 may be measured and / or calculated. Using this data set, the volumetric and / or mass flow rates through the blower 40 may be determined.
[0061] In the illustrated embodiment, the air filter device 20 includes a base filter element 42, a HEPA filter element 44, and an ambient air filter element 46. The base filter element 42 and the ambient air filter element 46 may include a sorbent, such as activated carbon. Here, the recirculated air flow 30 passes only through the base filter element 42. The filtered inflow 26 may pass through the ambient air filter element 46, the HEPA filter element 44, and the base filter element 42 in succession.
[0062] A bypass function for the filtered inflow 26 from outside can also be provided for the ambient air filter element 46 or the HEPA filter element 44. As shown diagrammatically in Fig. 2, the filtered inflow can for example bypass the HEPA filter element 44 and pass through the ambient air filter element 46 and the basic filter element 42. An external air quality sensor 48 can be provided to determine an indicator representative of the external air quality. Based on the measurements of the external air quality sensor 48, the electronic control unit 50 can determine whether the HEPA filter element 44 is bypassed by the filtered inflow 26 or not.
[0063] Furthermore, the electronic control unit 50 is configured to control the magnitude of the air flow 38 through the air filter device 20 and the recirculation ratio, i.e., magnitude of recirculated air flow 30 / magnitude of filtered inflow 26. To that end, a computer program according to the present invention is executed on the electronic control unit 50.
[0064] System information is provided to control the cabin air filtration system 12 (see step 102 of FIG. 3). At least one characteristic of the air filter device, including information about the overall filtering efficiency for the total inflow of air from the outside into the vehicle compartment; The magnitude of the airflow through the air filter device; and Vehicle speed and - It relates to the ratio of fresh air to recirculated air. At least one characteristic is efficiency curves of the filter media of the air filter device, in particular the efficiency curves of the basic filter element, the HEPA filter element and the ambient air filter element 42, 44, 46, respectively; the type of filter material of the installed filter elements 42, 44, 46; the pressure drop across the air filter device 20 as a function of the magnitude of the air flow 38 passing through the air filter device 20; and / or Includes information regarding the dust capacity of the air filter device 20, in particular the dust capacity of each of the base filter element, the HEPA filter element, and the ambient air filter elements 42, 44, 46.
[0065] An example of such system information is shown in Figures 4 and 5. Figures 4 and 5 show the ratio of recirculated air to fresh air (grey scale marked "A / R") through the air filter device 20 versus the overall filtering efficiency of the total fresh air inflow into the vehicle cabin (horizontal axis "Filtering efficiency") and the magnitude of the filtered air flow 38 (vertical axis "Airflow rate") at a given vehicle speed (e.g. 50 km / h). This information is provided for each pollutant, and in particular for particles of different size ranges, e.g. particles with an aerodynamic diameter of less than 10 μm (PM10) as in Figure 4 or particles with an aerodynamic diameter of less than 0.1 μm (PM0.1) as in Figure 5. As exemplarily shown in Figure 5, for a filtered air flow 38 of 150 m 3 / h, to achieve an overall filtration efficiency of 80% for PM0.1, the filtered air flow 38 should not contain more than 93% recirculated air 30.
[0066] Corresponding information can be provided for further particle sizes and / or harmful gases such as CO2, CO, NOx, etc. Furthermore, this information is provided for different vehicle speeds, e.g. 0 km / h, 30 km / h, 50 km / h, 100 km / h, 150 km / h.
[0067] The information exemplarily shown in Figures 4 and 5 may be provided in the form of a multi-dimensional data array, which may be contained in the electronic control unit 50 and may be contained in a computer program executed thereby.
[0068] The system information may be updated when one of the air filter elements 42, 44, 46 is replaced. The updated system information may be provided with the new filter element, for example on an RFID tag attached thereto, which may be read by an RFID reader installed in the air filter apparatus 20. Alternatively, the new filter element may instruct the electronic control unit 50 to obtain updated system information from a remote database, for example by providing a download link via the RFID tag.
[0069] The system information may include aging information, for example the extent to which the overall filtering efficiency of a filter element degrades as it is used or over a period of time.
[0070] In step 104, a required vehicle filtration efficiency is provided. There may be a different set of predefined limits for different contaminants, such as particulates of different size ranges. The ratio of fresh air to recirculated air is determined to meet these limits. For example, the predefined limits are: PM10: 20μg / m 3 less than, PM2.5: 20μg / m 3 less than PM1: 30μg / m 3 less than.
[0071] The ambient air outside the vehicle cabin is measured using an external air quality sensor 48 or a public measurement service to determine the concentration of PM10 at 10 μg / m 3 , PM2.5 is 5μg / m 3 , PM1 is 500 μg / m 3 Therefore, to achieve the PM10 and PM2.5 targets, no filtration is needed. But to achieve the PM1 target, an overall filtration efficiency of 1-30 / 500=94% is needed.
[0072] Alternatively or additionally, the geographic location of the vehicle 10 may be taken into consideration to provide the required filtration efficiency. The geographic location information may be obtained from the GPS antenna 52. For example, if the vehicle 10 is traveling through an area known for high pollution, a higher vehicle filtration efficiency may be required.
[0073] The required vehicle filtration efficiency is adjustable by the user of the vehicle 10. For example, the driver 16 can select between different air quality levels, such as normal or high air quality, predefined in the electronic control unit 50. For this purpose, an input / output device 54, such as a touch screen, may be provided.
[0074] In step 106, based on the required filtration efficiency provided in step 104, a recirculation ratio of fresh air and recirculated air is determined from the system information provided in step 102 for the current speed of the vehicle 10 and the current magnitude of the filtered air flow 38 such that the overall filtration efficiency is equal to the required vehicle filtration efficiency. For example, in a highly polluted environment, if the required vehicle filtration efficiency cannot be met while the windows of the vehicle 10 are open, the recirculation ratio is set to obtain the highest possible overall filtration efficiency. Note that the system information may take into account the effect of open windows and sunroofs.
[0075] If the vehicle speed is between two vehicle speeds for which system information is provided, then an interpolation method can be used to establish the relevant information to determine the required vehicle filtration efficiency. In particular, for both adjacent vehicle speeds, the multi-dimensional data array can be evaluated to determine the respective recirculation ratios. Linear interpolation can be applied to each result, i.e., the recirculation ratio, to obtain the recirculation ratio for the current vehicle speed.
[0076] Vehicle occupancy may be taken into consideration to determine the recirculation ratio in step 106. A seat occupancy sensor (not shown) may indicate the number of occupants 16, 18 in the vehicle 10. If the number of occupants 16, 18 is high, the proportion of recirculated airflow 30 may be limited to prevent fogging. Instead, a higher proportion of the filtered inflow 26 is directed through the air filter device 20.
[0077] Additionally, energy management information may be taken into account to determine the recirculation rate in step 106. For example, if the traction battery 56 is at a low charge level, the recirculation rate is determined to maintain adequate air quality while minimizing energy consumption for heating or cooling.
[0078] In step 108, the cabin air filtration system 12 is operated with the recirculation ratio determined in step 106. The electronic control unit 50 controls the flow ratio adjuster 32 accordingly. The determination of the recirculation ratio in step 106 and the adjustment of the recirculation ratio in step 108 may be repeated at predetermined time intervals, for example every second.
[0079] Cabin air filter operation according to steps 106 and 108 may be interrupted by periods of operation according to other strategies, step 110. For example, after a cold start in winter or parking in the sun in summer, defogging or speed ventilation may be prioritized over air quality.
[0080] The vehicle 10 may also include a cabin air quality sensor 58. The air quality within the cabin 14 may be communicated to the occupants 16, 18 via the input / output device 54. In particular, a display may be provided indicating that the air quality meets a selected air quality level. Additionally, a message may be displayed on the input / output device 54 indicating the remaining life of the filter elements 42, 44, 46 and / or when one of them needs to be replaced.
[0081] The measurements of the cabin air quality sensor 58 can also be used for the closed-loop control of the cabin air filter system 12. For example, the system information may be partially inaccurate due to a broken door seal. This may result in the control method according to steps 102-108 still being accurate for low vehicle speeds, but at high vehicle speeds, the unfiltered inflow may be higher than expected. This may result in more contaminants entering the cabin 14 from the outside. If this results in a deviation from the desired air quality in the cabin 14, the proportion of recirculated airflow 38 can be increased. Note that depending on the cause of the deviation from the desired air quality, it may also be necessary to reduce the proportion of recirculated airflow 38 in order to improve the air quality in the cabin 14.
[0082] Air from within the passenger compartment 14 can be allowed to exit the passenger compartment through one or more pressure reduction outlets 60. This can prevent excessive pressure build-up within the passenger compartment 14, especially when driving at high speeds. Furthermore, reducing the pressure in the passenger compartment 14 can reduce the energy consumption of the blower 40 to blow a sufficient amount of fresh air into the passenger compartment 14.
[0083] In summary, the present invention relates to a method of operating a cabin air filtration system (12) including an air filtration device (20) for filtering an air flow (38) entering into a passenger compartment (14) and consisting of fresh air from outside the passenger compartment (14) and recirculated air from inside the passenger compartment (14), wherein the magnitude of the air flow through the air filtration device is adjustable, and wherein the recirculation ratio of the air flow through the air filtration device to fresh air and recirculated air is adjustable, and wherein the total inflow (22) of air from outside is allowed to enter the passenger compartment as a filtered inflow (26) through the air filtration device (20) and an unfiltered inflow (28) bypassing the air filtration device, the method comprising: A) at least one characteristic of the air filter device, the characteristic including information regarding the overall filtering efficiency of the total inflow of air from the outside into the vehicle compartment; a magnitude of airflow through the air filter device; and Vehicle speed and providing system information relating to a recirculation ratio of fresh air to recirculated air; B) providing a required vehicle filtration efficiency; C) determining a recirculation ratio of fresh air to recirculated air from the system information for the current vehicle speed and current airflow magnitude such that the overall filtration efficiency corresponds to the required vehicle filtration efficiency provided in step B), and optionally operating the cabin air filtration system at said recirculation ratio.
[0084] The invention further relates to a computer program, an electronic control unit, each configured to support the execution of the method according to the invention, in particular configured to execute step B) and optionally step C).The invention further relates to a cabin air filter system configured to execute the method according to the invention. [Explanation of symbols]
[0085] Vehicle 10 Cabin Air Filter System 12 Cabin 14 Passengers 16 and 18 Air filter device 20 Total fresh air inflow from the external environment 24 22 filtration inflow 26 Unfiltered inflow 28 Recirculating Air Flow 30 Flow ratio adjustment device 32 Flap 34, 36 Filtered Air Flow 38 Blower 40 Basic filter element 42 HEPA filter element 44 Ambient air filter element 46 External Air Quality Sensor48 Electronic Control Unit 50 GPS antenna 52 I / O device 54 Battery 56 Vehicle Air Quality Sensor58 Pressure reducing outlet 60 Providing system information 102 Providing the necessary filtration efficiency104 Determining Recirculation Ratio106 Operate the cabin air filter system with the recirculation ratio from step 106 108 Operate the cabin air filtration system according to the high priority strategy.
Claims
1. A method of operating a cabin air filtration system (12) of a vehicle (10), comprising: The cabin air filter system (12) includes an air filter device (20) for filtering an air flow (38) flowing into a vehicle compartment (14), the air flow being composed of fresh air from outside the vehicle compartment (14) and recirculated air from inside the vehicle compartment (14); The size of the air flow (38) through the air filter device (20) is adjustable; The ratio of fresh air to recirculated air in the air flow (38) through the air filter device (20) is adjustable; A total inflow of air (22) from outside can enter the vehicle cabin as a filtered inflow (26) that passes through the air filter device (20) and an unfiltered inflow (28) that bypasses the air filter device (20), and the method includes: A) at least one characteristic of the air filter device (20), including information regarding the overall filtering efficiency for the total air inflow (22) from the outside into the vehicle compartment (14); the magnitude of the air flow (38) through the air filter device (20); Vehicle speed and providing (102) system information relating the fresh air to the recirculation ratio of the recirculated air, the overall filtration efficiency being determined based on the variables: magnitude of the air flow (38) through the air filter device (20), the vehicle speed, and the ratio of the fresh air to the recirculated air; B) providing a required vehicle filtration efficiency (104); C) determining (106) from the system information a recirculation ratio of the fresh air to the recirculated air for a current vehicle speed and a current airflow magnitude such that the overall filtration efficiency corresponds to the required vehicle filtration efficiency provided in step B).
2. The method of claim 1 , wherein the system information comprises a multi-dimensional data array having an output value representing a recirculation ratio of the fresh air to the recirculated air.
3. 3. The method of claim 2, wherein an interpolation method is used to determine the recirculation ratio of said fresh air to said recirculated air.
4. 2. The method of claim 1, further comprising determining a recirculation ratio of said fresh air to said recirculated air at predetermined time intervals and adjusting the flow ratio to said ratio.
5. The method of claim 1 , wherein the system information is provided for different contaminants, in particular for particles of different size ranges.
6. 2. The method of claim 1, wherein the system information is updated upon installation of a new air filter element (42, 44, 46) in the air filter device (20).
7. 2. The method of claim 1, wherein the system information takes into account the aging of the vehicle and / or the aging of the air filter elements (42, 44, 46) of the air filter device (20).
8. The method of claim 1, wherein the required vehicle filtration efficiency is provided as a function of the geographic location of the vehicle (10).
9. The method of claim 1 , wherein the required vehicle filtration efficiency is provided as a function of an environmental pollution measurement.
10. 10. The method of claim 9, wherein the required vehicle filtration efficiency is determined to meet different predetermined limit values for different pollutants, in particular for particles of different size ranges.
11. 2. The method of claim 1, wherein the required vehicle filtration efficiency is provided according to settings of an electronic control unit (50) of the cabin air filter system (12), in particular, the settings of the electronic control unit (50) being adjustable by a user and / or by automatic control.
12. 2. The method of claim 1, wherein in step C) the occupants of the vehicle (10) are taken into account to determine the recirculation ratio of the fresh air to the recirculated air.
13. 2. The method of claim 1, wherein in step C) energy management information of the vehicle (10) is taken into account to determine the recirculation ratio of the fresh air and the recirculated air.
14. 2. The method of claim 1, further comprising operating the cabin air filter system at the recirculation rate, wherein operation of the cabin air filter system at the recirculation rate according to step C) is interrupted by periods of operation of the cabin air filter system at an air recirculation rate provided by a higher priority strategy, in particular for defogging, defrosting, speed ventilation, or energy conservation.
15. The air filter device (20) comprises: a basic filter element (42) for filtering the fresh air and the recirculated air; 10. The method of claim 1, further comprising: a HEPA filter element (44) and / or an ambient air filter element (46) for filtering the fresh air.
16. the ambient air filter element (46) is located upstream of the HEPA filter element (44); and / or 16. The method of claim 15, wherein the basic filter element (42) and / or the ambient air filter element (46) comprises at least one adsorbent, in particular activated carbon.
17. The method of claim 1 , wherein the cabin air filtration system (12) comprises a passenger compartment air quality sensor (58) and / or an exterior air quality sensor (48).
18. 16. The method of claim 15, wherein the fresh air flow through the air filter device (20) passes through or bypasses the HEPA filter element (44) and / or the ambient air filter element (46) depending on measurements from a passenger compartment air quality sensor (58) and / or an exterior air quality sensor (48) and / or an estimate of air quality outside and / or inside the passenger compartment (14).
19. 18. The method of claim 17, wherein the required vehicle filtration efficiency is provided in response to measurements from the cabin air quality sensor (58) and / or the exterior air quality sensor (48) and / or estimates of air quality outside and / or inside the cabin (14).
20. The method according to any one of claims 17 to 19, wherein an air quality index or a remaining life is reported, in particular based on measurements of the passenger compartment air quality sensor (58).
21. The at least one characteristic of the air filter device (20) is: the efficiency curve of the filter material of the air filter device (20); The type of the filter material; the pressure loss across the air filter device (20) as a function of the magnitude of the air flow (38) passing through the air filter device (20); and / or The method of claim 1, further comprising information regarding the dust capacity of the air filter device (20).
22. 1. A computer program for controlling a cabin air filtration system (12) of a vehicle, comprising: The cabin air filter system (12) includes an air filter device (20) for filtering an air flow (38) flowing into a vehicle compartment (14), the air flow being composed of fresh air from outside the vehicle compartment (14) and recirculated air from inside the vehicle compartment (14); The size of the air flow (38) through the air filter device (20) is adjustable; The ratio of fresh air to recirculated air in the air flow (38) through the air filter device (20) is adjustable; a total inflow (22) of air from outside can flow into the vehicle cabin as a filtered inflow through the air filter device (20) and an unfiltered inflow (28) bypassing the air filter device (20); The computer program is configured to cause an electronic control unit (50) of the cabin air filtration system (12) on which the computer program is executed to: At least one characteristic of the air filter device (20) including information regarding the overall filtering efficiency for the total air inflow (22) from the outside into the vehicle compartment (14); the magnitude of the air flow (38) through the air filter device (20); Vehicle speed and and determining, from system information relating the recirculation ratios of the fresh air and the recirculated air, a recirculation ratio of the fresh air to the recirculated air such that the overall filtration efficiency corresponds to a required vehicle filtration efficiency for a current vehicle speed and a current magnitude of air flow (38).
23. 23. The computer program of claim 22, further comprising instructions for causing the electronic control unit (50) on which the computer program is executed to determine the required vehicle filtration efficiency.
24. An electronic control unit (50) for a vehicle cabin air filtration system (12), comprising: The cabin air filter system (12) includes an air filter device (20) for filtering an air flow (38) flowing into a vehicle compartment (14), the air flow being composed of fresh air from outside the vehicle compartment (14) and recirculated air from inside the vehicle compartment (14); The size of the air flow (38) through the air filter device (20) is adjustable; The ratio of fresh air to recirculated air in the air flow (38) through the air filter device (20) is adjustable; a total inflow (22) of air from outside can flow into the passenger compartment (14) as a filtered inflow (26) that passes through the air filter device (20) and an unfiltered inflow (28) that bypasses the air filter device (20); The electronic control unit (50) At least one characteristic of the air filter device (20) including information regarding the overall filtering efficiency for the total air inflow (22) from the outside into the vehicle compartment (14); the magnitude of the air flow (38) through the air filter device (20); Vehicle speed and and an electronic control unit (50) configured to determine, from system information relating the recirculation ratios of the fresh air and the recirculated air, a recirculation ratio of the fresh air to the recirculated air such that the overall filtration efficiency corresponds to a required vehicle filtration efficiency for a current vehicle speed and a current magnitude of air flow (38).
25. 25. The electronic control unit (50) of claim 24, wherein the electronic control unit (50) is further configured to determine the required vehicle filtration efficiency.
26. A cabin air filter system (12), comprising: an air filter device (20) for filtering an air flow (38) flowing into the vehicle compartment (14), the air flow being composed of fresh air from outside the vehicle compartment (14) and recirculated air from inside the vehicle compartment (14); a blower (40) for adjusting the size of the air flow (38) through the air filter device (20); a flow ratio adjusting device (32) for adjusting the ratio of fresh air to recirculated air in the air flow (38) passing through the air filter device (20); A cabin air filter system (12) comprising an electronic control unit (50) according to claim 24 or 25.
27. 27. A vehicle comprising the cabin air filter system of claim 26.